PSoC Creator & Designer Software

[Anonymous]

Hello EveryBody,

   

I am using PSOC 5LP Kit and i want to implement instrumentation amplifier having high CMRR and Gain. How i can do this?

   

Looking forward for your suggestions.

       

Regards

   

Awais

[JoMe_264151]

Please post only once in this forum, your questions will be red and answered by the time.

   

There is an Application Note concerning the same question in PSoC3 which will be the same for your PSoC5

       

Bob

[Anonymous]

Thank you so much for your reply.

   

Actually i am new on this forum.

   

Next time i will keep this thing into account.

       

Regards

   

Awais

[JoMe_264151]

You are always welcome!

   

BTW: Where in Germany are you located? I live near Bremen.

       

Bob

[Anonymous]

I live in Bremen. And working in Uni Bremen.

   

Awais

[Anonymous]

Are u living in Bremenhaven?

[JoMe_264151 · Accepted solution]

Living in Zeven. The son of my wife is studying at Bremen, too (nearly ready).

   

Bob

[Anonymous]

Ah ok.

   

I am using cypress kit for the first time and it is very interesting. I am just trying to convert my hardware onto this chip.

   

Sorry! I dont want to click "answer verified" but did it mistakenly. I just wanted to click reply.

   

i dont know what happened with this.

   

Does it make anything negative?

[JoMe_264151]

I even do not know what the "Answer verified" click does at all (except inserting that note into the post). So nothing to get upset for.

       

Bob

[Anonymous]

Ah ok!

   

Thx 🙂

[ETRO_SSN583]

Do NOT use that ap note that Bob posted.

       

You cannot because of the G mismatch between PGA (if you tried using those)

   

or the Aol mismatch one OpAmp to another. Depends in latter case how much

   

CMRR you are willing to forego. In the former case the CMRR is horrible worst

   

case becuse of G inaccuracy PGA to PGA.

       

Here is a analysis - http://www.cypress.com/?app=forum&id=2492&rID=82151

       

https://www.dropbox.com/s/plck7e95v7pw33c/CMR%20Analysis%20IA.pdf?dl=0

       

Use an external IA. Or a single stage IA with 1 OpAmp and external precision Rs.

       

       

But 2 and 3 OpAmp architectures, only use an external IA.

       

Regards, Dana.

[Anonymous]

Thank you so much Every Body 🙂

[ETRO_SSN583]

Glad to have been of help.

       

Regards, Dana.

[Anonymous]

Hi,

   

Actually I tried to make an instrumentation amplifier"Pic is attached". I dont understand its behaviour.

   

I applied 400mv to VDAC1 and 100mv to VDAC2.

   

Could please help me to analyse its behavior?

   

Looking forward for your suggestions.

   

Regards

   

Awais

[JoMe_264151]

Well, to explain how your IA behaves would need some description of "how" it behaves.

   

Additionally I would suggest you to post your complete project, so that we all can have a look at all of your settings? To do so, use
Creator->File->Create Workspace Bundle (minimal)
and attach the resulting file.



Bob
 

[Anonymous]

Here Are my files

[Anonymous]

This is my complete project file.

       

I want to check is this amplifier is fully correct or not. I am lost now 😞

   

Dont know whats going on 😞

[Anonymous]

Please do not confuse with the name (PSOC 3). I made this project for PSOC 5LP.

[ETRO_SSN583]

Unless you dont need much CMR in the input stage do NOT use that solution.

       

If you do the analysis on this you will get << 20 db CMR because of PGA gain accuracy

   

as stipulated in datasheet. See the analysis in the earlier post.

       

Regards, Dana.

       

[Anonymous]

Actually i need very high CMRR (More or less 80 to 90 DB).

   

If This will not work then, is there any other possiblity to get the result near to my desired value?.

[ETRO_SSN583]

You will have to unequivocally use an external IA to achieve that.

       

www.dropbox.com/s/plck7e95v7pw33c/CMR%20Analysis%20IA.pdf

       

Regards, Dana.

[Anonymous]

I also tried to implement instrumentation amplifier with three op amps but that was was also giving me strange results.

[ETRO_SSN583]

If you use 3 OpAmps and a precision thin film R network for the

   

Rs you can get approach that level of CMR, but OpAmp AOL

   

differences and mismatch thermals, offsets, will limit you.

       

External precision IA is the way to go if you need lots of G and CMR.

       

Regards, Dana.